Heliothis zea is an insect which is more commonly known as the cottonboll worm, the corn ear worm, or the tomato fruit worm. This insect annually damages large quantities of corn, cotton and tomatoes.
Heliothis virescens is an insect which is more commonly known as the tobacco budworm. This insect also annually infests and damages large quantities of cotton as well as tobacco plants.
Due to environmental concerns about insecticides, individuals have explored alternative methods for eradicating these pests. One such method uses pheromones in order to disrupt the mating and subsequent reproduction of these insects.
Pheromone is the name given to a wide variety of organic compounds which fulfill a quasi-hormonal, or more accurately, an intraspecies communicational role. The female insect produces a minute amount of the pheromone which is detected by the male of the species and aids him in finding and mating with a female. Sex pheromones have enormous potential in insect control as they appear to be harmless to other forms of life and are relatively species specific. They may be used in a number of ways.
One such way is mating disruption. In mating disruption a sufficient quantity of the pheromone is distributed throughout a field so that the atmosphere is permeated with the pheromone. With the pheromone everywhere, the insect has great difficulty in locating a mating partner and therefore will be prevented from reproducing.
It is known that the mating of both Heliothis zea and Heliothis virescens can be disrupted by a 16:1 mixture of Z-11-hexadecen-1-al and Z-9-tetradecen-1-al.
Although this mixture is useful as a mating disruptant, known synthetic routes for its production are too cumbersome and expensive to be conducted economically in a large scale synthesis.
For example, U.S. Pat. No. 3,917,711 discloses a method for producing a admixture of Z-11-hexadecen-1-al and Z-9-tetradecen-1-al which comprises oxidizing a Z (cis) 9-tetradecenol into its corresponding aldehyde and Z (cis) 11-hexadecen-1-al from its corresponding alcohol. However, in such a process the starting materials must be isomerically pure. This can be accomplished by purchasing commercially available C-14 or C-16 alcohols and subjecting them to chromatography to separate the cis and trans isomers. However, this method is not amendable to being carried out economically on a large scale basis due to the stereochemical restraints.
Thus, it would be a valuable contribution to the art to develop compounds having pheromone-like activities for the pests Heliothis zea and Heliothis virescens that do not have to be isomerically pure, and can be economically produced.